1. Field of the Invention
This invention relates to a production method of a spinning ring for a ring spinning machine for integrally forming a ring flange portion, a neck portion, a support flange portion and a fit-in portion of a ring for a ring spinning machine for use in ring spinning machinery such as a ring spinning frame and a ring twisting frame, by cold rolling.
2. Description of the Prior Art
Production methods of a spinning ring for a ring spinning machine, particularly a non-reversible ring for a ring spinning machine, generally comprise the following steps (a-1) to (a-6):
(a-1): A pipe material or a round bar of a case hardening steel or a high carbon chromium bearing steel is used as a blank, and the blank is cut or hot forged into a cylindrical blank material 119 a cross-section of which is shown in FIG. 6 (blank material forming step).
(a-2): The blank material is subjected to cutting by a lathe to form a spinning ring 118 for a ring spinning machine having a predetermined shape a cross-section of which is shown in FIG. 6 (cutting step).
(a-3): Heat-treatment such as quenching and tempering is applied to the spinning ring 118 shaped into the predetermined shape described above (heat-treatment step).
(a-4): The surface of the spinning ring 118 so heat-treated is polished by barrel polishing, etc. (polishing step).
(a-5): Surface treatment such as plating and coating is applied to the surface of at least the ring flange portion of the spinning ring 118, whenever necessary (surface treatment step).
(a-6): After final inspection, the spinning ring 118 for a ring spinning machine is obtained as the product.
In the conventional production method of the non-reversible ring for a ring spinning machine comprising the steps (a-1) to (a-6), the cylindrical blank material 119 shown in FIG. 6 is produced from the pipe material or the round bar and this blank material is then subjected to cutting to form the spinning ring 118 for a ring spinning machine having the predetermined shape shown in FIG. 6. Therefore, the blank material 119 must have a sectional shape whose size can contain the sectional shape of at least the spinning ring 118 for a ring spinning machine. Therefore, the weight of the blank material 119 is about 5 to about 10 times the weight of the spinning ring 118 for a ring spinning machine, and there remains the problem that the yield of the material is extremely low.
When the round bar, in particular, is hot forged to form the cylindrical blank material 119 by these conventional production methods, the round bar is cut first into a predetermined length, is then shaped into a predetermined cylindrical shape by hot forging, and is spheroidally annealed so as to spheroidize the structure of the blank material 119. Furthermore, shot blast is carried out to remove the carburized scale formed during hot forging and to remove the black scale of the surface before obtaining the blank material 119. Therefore, there remains the problem that the production cost of the blank material 119 is extremely high.
When the non-reversible ring for a ring spinning machine is produced by these conventional production methods, the blank material 119, for example, is first clamped at one of the end portions thereof by the lathe for cutting, and under this state, the outer peripheral surface of the other end portion of the blank material 119 is cut to form a fit-in portion of the spinning ring. Next, the inner peripheral portion of the blank material 119 is cut to form the inner drum portion of the spinning ring. Thereafter, the blank material 119 is clamped once again to grip the other end portion thereof, the other portions of the blank material 119 such as the ring flange portion, the neck portion and the support flange portion are cut under this state to form the spinning ring 118 for a ring spinning machine. Accordingly, at least two production steps are necessary to form the spinning ring 118 for a ring spinning machine, and the problem remains in that the production process is complicated.
According to these conventional production methods, the outer peripheral surface of the portions which become the product are gripped. Therefore, the gripped portions are scratched and the cutting trace remains on the ring flange portion. In some cases, these scratches and cutting traces cannot be removed by the post-step, and they affect adversely the wear of a traveller.
According to these conventional production methods, further, the metal flow of the blank material 119 is cut off and this cut portion of the metal flow appears on the surface of the ring flange portion (running surface of the traveller). Therefore, the fatigue resistance drops, and life of the spinning ring for a ring spinning machine is reduced.